The invention relates generally to a method, apparatus, and system for packaging oxygen sensitive materials, and particularly to a method, apparatus, and system for triggering an oxygen scavenging film.
It is well known that limiting the exposure of oxygen sensitive articles to oxygen maintains and enhances the quality and shelf life of the article. For instance, by limiting the oxygen exposure of oxygen sensitive food articles in the packaging system, the quality of the food article is maintained and spoilage is reduced. In addition, such packaging also keeps the article in inventory longer, thereby reducing restocking costs, and costs incurred from waste.
Commonly used packaging systems include modified atmosphere packaging (MAP) and vacuum packaging in conjunction with oxygen barrier films. In these instances, reduced oxygen environments are employed at the time of packaging, while the oxygen barrier film reduces the amount of oxygen that physically enters the package during storage.
U.S. Pat. No. 5,211,875 to Speer et al. discloses methods and compositions for scavenging oxygen. The xe2x80x9coxygen scavengerxe2x80x9d materials disclosed by Speer et al. are compositions which consume, deplete or reduce the amount of oxygen from a given environment.
Oxygen scavenging materials are useful in MAP and barrier packaging environments. However, oxygen scavenging materials typically require triggering or activation to bring on the oxygen scavenging properties, and delays referred to as an induction period are sometimes experienced before the onset of useful oxygen scavenging properties. Compositions exhibiting lengthy induction times must be held by an end user in inventory for a sufficient period of time before use. On the other hand, oxygen scavenging compositions having a shorter induction period must be used within a relatively short period of time so that the oxygen scavenging properties of the material are not prematurely exhausted.
The need remains for an effective method of triggering an oxygen scavenger film so as to trigger oxygen scavenging properties when desired; preferably a method having a short induction period so that the film can be triggered at or immediately prior to use during packaging of an oxygen sensitive article; and preferably one which is simple and readily incorporated into existing packaging procedures.
The need also remains for an apparatus for triggering an oxygen scavenging film so as to provide the film with a short or negligible induction period; preferably enhanced oxygen scavenging rate and longevity; preferably an apparatus which is readily incorporated in-line into existing packaging systems for triggering oxygen scavenging film at or immediately prior to packaging.
In a first aspect of the invention, a method for triggering an oxygen scavenging film comprises providing an oxygen scavenging film comprising an oxidizable organic compound; and exposing the film to a source of UV-C light at a wavelength, intensity, and residence time sufficient to provide the film with a dose of UV-C light of at least 100 mJ/cm2.
In a second aspect of the invention, an in-line method for packaging comprises providing an oxygen scavenging film comprising an oxidizable organic compound; exposing said film to a source of UV-C light having a wavelength of between 200 and 280 nm at an intensity and residence time sufficient to provide said film with a dose of UV-C light of at least 100 mJ/cm2 so as to provide a triggered film; feeding said triggered film to a means for packaging an article, and applying said triggered film to said article so as to provide an oxygen scavenging package.
In a third aspect of the invention, an apparatus for triggering an oxygen scavenging film comprises means for emitting UV-C light having a wavelength of between 200 nm and 280 nm; means for defining a film path associated with the means for emitting UV-C light; and means for feeding a film having an oxidizable organic compound to the film path whereby the film is exposed to a dose of the UV-C light of at least 100 mJ/cm2 so as to provide a triggered film.
In a fourth aspect of the invention, a packaging system comprises means for emitting UV-C light having a wavelength of between 200 nm and 280 nm; means for defining a film path associated with said means for emitting UV-C light; means for feeding a film having an oxidizable organic compound to said film path whereby said film is exposed to a dose of said UV-C light of at least 100 mJ/cm2 so as to provide a triggered film; means for feeding said triggered film to a means for packaging articles; and means for applying said triggered film to the articles to make packages; whereby said triggered film is continuously triggered and incorporated into said packages so as to provide oxygen scavenging packages.